>the plastic can easily withstand temperatures greater than that needed for
wax to melt.  I would simply but the frame in boiling water until the wax
melts then remove the frame.

Wax melts at about 145 F. The water would only need to be a bit more than
that wouldn't it? I'm not sure I'd want boiling water. I tried to reclaim
some plastic foundations a few years back by placing them in a solar melter
for a short period of time, and in a short period of time they were no
longer suitable for use in a Langstroth hive.

Regards,
Dick